Incidence and survival of childhood Langerhans cell histiocytosis in Northwest England from 1954 to 1998

BACKGROUND: Langerhans cell histiocytosis (LCH) is a rare proliferative disorder of pathological Langerhans cells, for which the aetiology and pathogenesis remain largely unknown. PROCEDURE: Information on the 101 children with LCH registered with the population-based Manchester Children's Tumour Registry (MCTR) between 1954 and 1998 was extracted from the records of the MCTR. This included age, sex, date of diagnosis, systems affected at diagnosis and follow-up. RESULTS: The overall incidence rate for LCH was 2.6 cases per million child years. In those under 1 year of age the incidence rate was 9.0 cases per million child years, compared to 0.7 cases per million in those aged 10-14 years (P < 0.0001 for age trend). There was no evidence of seasonal variation in presentation by month of birth or first symptom. Bone was the most common site of disease involvement (67% of cases), followed by skin (37%) and soft tissue (22%). The overall survival rate has improved over time, from 57% in 1954-1968 to 74% in 1985-1998. Ninety percent of deaths were due to disease progression, the remainder were due to complications of intensive therapy. The site of LCH lesions and extent of disease present at diagnosis strongly predicted survival outcome. Patients with initial liver involvement had a 5-year survival rate of 25% compared with 93% for those with bone lesions alone at diagnosis. CONCLUSIONS: Incidence rates varied significantly by age at diagnosis, and have been stable over time. Survival has improved considerably over time, but varies strongly by age and systems affected at diagnosis.